Which do and which dont?

is it that the goldstar systems have a protection that prevents em from playing backups, or is it just the quality of the lazer? (ie; turbo duo or sega cd units all play em fine, its just the media you use that can screw it over)

Just go to your local Wal-Mart / Target / K-Mart / etc. and look for closet shoe shelves. They're about a yard high with two shelves for a pair of shoes on each. I've got one of those sitting on my dresser beside my entertainment center. Put one system on the bottom, one on each shelf, and one on the very top.